There are very few edible minerals, the best known of which is rock salt, which plays an essential role in the human diet. In addition, various products made for human and/or animal consumption may contain minerals, such as zeolites or dolomite, and cosmetics are also not without mineral constituents (for example, talc in dusting powder). The minerals used as gemstones are not harmful to our health either. However, many minerals are toxic, namely those that contain some toxic element or heavy metals (lead, cadmium, etc.). Such are the arsenic sulphides (realgar, pararealgar, orpiment), which attract attention with their red, orange or yellow colour. They can be found in several places in Covasna County, where they are still formed by volcanic exhalations.
In the picture: Pararealgar, Covasna (Romania). Size: 18 cm. Photo by Géza Kulcsár.